Blackboard



(No Model.)

0. E. GREGORY.

BLAGKBOARD.

No. 572,004. Patented Nov. 24, 1896.

Witnesss. In ventor.

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UNITED STATES PATENT OFFICE.

CHARLES EZRA GREGORY, OF NASHVILLE, TENNESSEE.

BLACKBOARD.

SPECIFICATION forming part of Letters Patent No. 572,004, dated November24, 1896. Application filed April 29, 1896. Serial No. 589,540. (Nomodel.)

T 0 all whom it may concern.-

Be it known that 1, CHARLES EZRA GREG- ORY, a citizen of the UnitedStates, residing at Nashville, in the county of Davidson and State ofTennessee, have invented certain new and useful Improvements inBlackboards; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains. to make and use the same. 1

The object of my said invention is to provide a blackboard with asurface adapted for practical and successful use with crayons of naturaltalc. Many attempts have heretofore been made to produce such a board,but with only partial success, of varying degrees, as a result. Toproduce such a board, I have first provided a composition for surfacingthe material of which its base or body is composed, which when properlyapplied will produce the required surface, and, secondly,have devisedthe practically successful method of applying the same. These steps orelements, which together constitute my said invention and result in thecharacter of blackboard desired, will first be fully described, and thensummed up in the claims.

The. accompanying drawing illustrates a section of blackboard of myimproved construction. It is composed of a cloth or fabric back a, facedwith paper I), on which my improved surface a is mounted, as will behereinafter more fully described, no special description of the boardbeing necessary, except what will be incidental to the description ofthe method employed in producing the same.

The composition for surfacing or enameling the board is composed of thefollowing ingredients in substantially the proportions stated: grain orwood alcohol, one gallon; gum-shellac, three pounds; black oXidmanganese, three and three-fourths pounds; ultramarine-blue, six ounces;lampblack, eight ounces; isinglass, two ounces; saturated solution ofguiac, eight ounces; Venice turpentine, eight ounces; fiour of talc,eight ounces. The leading element of said composition is black oxid ofmanganese, together with guiac and isinglass combined with the shellac,and it is the combination of these elements which mixture to the shellacsolution.

one quart'of alcohol with one quart of water .half hour or until it isdissolved.

- I regard as of the most importance in the accomplishment of thedesired end. Said composition is prepared as follows: First, dissolvethe shellac in the alcohol and strain through a fine piece of muslin orcheese-cloth. Sift the black oxid of manganese through silkbolting-cloth, about No. 15, and use only that which passes through saidcloth. Mix said manganese, the flour of talc, the lampblack, and theultramarine-blue together. Add this Then dilute and in this place thetwo ounces of isinglass and place over a gentle heat and stir for aWhile warm strain through a piece of fine muslin or cheese-cloth. Thenadd this mixture to the first mixture by pouring in slowly and stirringall the time upon the principle of trituration. Then add the guiac andVenice turpentine. Thoroughly mix the whole and then allow it to standfor twelve or more hours, when it is complete and ready for use.

The board is made as follows: First, take good quality of strong fabric,such as sheeting, of the desiredsize, torn from the piece to insure thatthe edges run with the grain. Submerge the same in water and then wringout and spread on a smooth table prepared to receive it. Stretch itasmuch as possible in each direction and secure by tacking, placing thetacks about three inches apart. Then take a piece of good all jute orManila paper of corresponding size and secure to the fabric. This isdone preferably by good flourpaste, in which is placed a quantity ofgood quality Venice turpentine, the paper being first thoroughly coatedwith the paste, the

cloth then coated or sized with the same and 'stir and shake the mixturethoroughly until Pour a small.

all sediment is in suspense.

quantity (a pint is sufficient ordinarily) into a shallow vessel andapply with a chiselpointed brush (a four-inch brush will be foundsuitable) crosswise of the paper, coating the entire surface in acrosswise direction. Allow this coat to thoroughly dry,which usuallyrequires about one hour. Rub the surface thus formed gently with No. 1emerypaper and then apply another coat of the mixture in the reversedirection,the operation being repeated in the same manner until therequired number of coats have been applied to produce the surfacedesired. In practice I have found that five coats make a most desirablesurface for the purpose, and this is the number I usually employ. Afterthe last coat has been applied it should be allowed to dry and hardenfor several hours, (six are usually sufficient,) and then the entiresurface should be rubbed with a block of natural tale to render itsmooth. Then the talc-flour is brushed off and the surface again rubbedwith felt or cloth until the surface is perfectly clean and black, whenthe board material is finished and ready for use. It is taken from thetable by cutting just inside the tacks, and may be made in panels of anysize desired.

The board may be mounted in any suitable manner desired, either directlyon the wall or on a frame. I mount them in three ways by cementing orpasting to the wall; by what is termed the shrinking process,whichconsists in sponging the back with water and allowing it to soak for tento fifteen minutes, and then nailing to the wall or frame in the samemanner as before described for securing to the table; It is then allowedto dry and shrink, and in twenty-four to forty-eight hours it will drawperfectly taut and be ready for use; and I also mount them on veneering,either two or three ply, in the following manner: First, cover the faceside of the veneering with any kind of soft heavy paper securelyattached by means of cement or paste. Then take a piece of the board tobe mounted, of corresponding size, and secure it to the soft paper thathas been secured to the veneering. This is done by thoroughly coatingthe cloth or back of the board with cement or paste and then coating orsizing the paper that has been secured to the veneering. Then apply theprepared board and roll with rollers in same manner as described inuniting the jute or Manila paper to the cloth, and in twenty-four hoursit is ready for use. The object of placing the paper between the boardand the veneering is to render the board, when completed, non-resonant.

The blackboard thus made has been found after extensive experiment to bea perfect blackboard for the purpose first stated. Natural talc crayonswrite upon it easily and smoothly, making a clear mark without, evenafter long use, in any manner injuring or scratching or cutting thesurface. The marks are very easily removed by simply wiping with a drypiece of cloth or, preferably, a felt eraser. No water is required forcleaning it, as the felt eraser cleans the surface perfectly and leavesit clean and black.

I do not claim a board made up of the fabric and paper with an enamelsurface, as I am aware that boards have long been so made. I am alsoaware that some of the elements of my composition have long been used incompositions for such surfaces; but I am not aware that black oXid ofmanganese in any combination or with guiac, flour of talc, andisinglass, as described, has ever heretofore been prepared and used inthe manner herein described, and to this element and combination is duethe great value of this composition over others that are well known.

Having thus fully described my said invention, what I claim as new, anddesire to secure by Letters Patent, is-

1. A composition for surfacing blackboards consisting of black oXid ofmanganese and isinglass combined with other adhesive and coloringelements, substantially as set forth.

2. A blackboard provided with a surface of a composition made up ofshellac, black oxid of manganese, ultramarine-blue, guiac, flour oftalc, Venice turpentine, lampblack and isinglass in solution withalcohol and water, substantially as set forth.

3. A composition for surfacing or enameling blackboards consisting ofisinglass and black oxid of manganese dissolved and combined withbody-making and coloring elements including shellac, substantially asset forth.

4.. The process of makinga composition for surfacing or enamelingblackboards in which isinglass is used as an ingredient, which consistsin dissolving said isinglass in water and alcohol, and adding shellacdissolved in alcohol, and other body-making and color-giving elements,substantially as set forth.

5. The process of making a composition for surfacing or enamelingblackboards which includes both isin glass and shellac which consists indissolving said isinglass in water'and alcohol and dissolving theshellac in alcohol and combining the solutions with each other and withother adhesive, body-making and color giving elements, substantially asset forth.

6. The process of makingablackboard-surfacing composition containingshellac and isinglass, which consists in dissolving the shellac inalcohol and the isinglass in water and alcohol and then uniting the twosolutions with each other and the other elements of the composition,substantially as set forth.

7. The process of making surfacing composition for blackboards, whichconsists in dissolving shellac in alcohol, then adding black oxid ofmanganese, guiac, Venice tur pentine, fiour of talc, lampblack and blue,then adding a solution of isinglass in water and alcohol, substantiallyas set forth.

8. The process of preparing the surface of finishing and cleaning withfelt or cloth, sub- 10 a blackboard with the composition herein setstantial ly as set forth.

forth, which consists in applying said com- In testimony whereof I affixmy signature position to said surface in one direction, then in presenceof two witnesses.

5 rubbin down the same then applyin anw other c oat in the otherdirection, then rub- CHARLES EZRA GREGORY bin g it down again, andrepeating the opera- Witnesses: tion until the desired thickness issecured, HARDIN LEEOH,

and then rubbing with a block of talc and W. K. PATTERSON.

